Field of the Invention
The invention relates to an optical electrical module. Particularly, the invention relates to an optical electrical module used for optical communication.
Description of Related Art
In a field of optical communication, a signal transmitter uses an optical electrical module that serves as a signal transmitting element to convert an electric signal into an optical signal, and a signal receiver uses the optical electrical module that serves as a signal receiving element to convert the received optical signal into the electric signal. Therefore, the optical electrical module is an indispensable device in the field of optical communication.
FIG. 1 is a schematic diagram of a conventional optical electrical module. Referring to FIG. 1, the conventional optical electrical module 100 is used to provide a light signal, and includes a circuit board 110, a base 120, a light-emitting element 130, an optical fiber 140 and a chip 150. The base 120 and the chip 150 are disposed on the circuit board 110, and the chip 150 is electrically connected to the circuit board 110 through a bonding wire 162. The base 120 has surfaces 122 and 123 parallel to a bottom surface 121 thereof. A reflective surface 124 of the base 120 is connected to the surfaces 122 and 123 and located between the surfaces 122 and 123, and tilts a predetermined angle relative to the surface 123. The light-emitting element 130 is disposed on a pad 125 on the surface 122, and is electrically connected to the chip 150 through the pad 125 and a bonding wire 164. A part of the light-emitting element 130 protrudes out of the pad 125 and faces the reflective surface 124. The optical fiber 140 is disposed on the surface 123 of the base 120.
The chip 150 is adapted to control the light-emitting element 130 to emit a corresponding light signal 132 according to information to be transmitted, and the reflective surface 124 reflects the light signal 132 into the optical fiber 140 for transmitting the light signal. 132 through the optical fiber 140. Moreover, a signal receiver can use another optical electrical module to receive the light signal 132 transmitted by the optical fiber 140. The optical electrical module used for receiving the light signal 132 is similar to the optical electrical module 100, and a difference there between is that the light-emitting element 130 is replaced by a light-receiving element.
In the conventional optical electrical module 100, since a part of the light-emitting element 130 protrudes out of the pad 125 to facilitate providing the light signal 132 to the reflective surface 124, a contact area between the light-emitting element 130 and the pad 125 is relatively small. Therefore, the light-emitting element 130 can easily fall off, which leads to poor reliability of the optical electrical module 100. Similarly, the conventional optical electrical module used for receiving the light signal also has the problem that the light-receiving element can easily fall off.
Packaging of the optical device is one of key techniques that influence a yield and a cost of the optical electrical element and the optical electrical module. Referring to FIG. 2, FIG. 2 is a schematic diagram of a package structure of another optical electrical module according to the conventional technique. The optical electrical module 100A includes a circuit board 101, a light-emitting/receiving element 103, an optical fiber 104 (which is also referred to as waveguide), a substrate 102 and a cover plate 106. The substrate 102 is disposed on the circuit board 101. The light-emitting/receiving element 103 is disposed on the substrate 102. The optical fiber 104 used for transmitting a light signal 105 is disposed on the substrate 102. The light signal 105 can be transmitted to the light-emitting/receiving element 103 through a reflective surface 102a of the substrate 102.
Since the optical fiber 104, the reflective surface 102a and the light-emitting/receiving element 103 have to be accurately aligned, a microscope is used with assistance of a special tool to adjust a position of the cover plate 106, so as to fix the optical fiber 104 on the substrate 102, and then follow-up packaging steps are performed. Such practice requires a highly skilled worker, which not only has a high cost, but also has low process robustness. Therefore, an advanced fixing module is required to be provided to facilitate the packaging process of the optical device and ameliorate the process robustness and yield.
FIG. 3 is a partial cross-sectional view of an optical electrical module of a conventional technique that is used for sending a light signal, and FIG. 4 is a three-dimensional exploded view of a substrate and an optical fiber of FIG. 3. Referring to FIG. 3 and FIG. 4, the conventional optical electrical module 100B includes a substrate 110B, a plurality of light-emitting element 120B and a plurality of optical fibers 130B. The substrate 110B has a plurality of strip grooves 112B parallel to each other, and the strip grooves 112B, for example, extend along a straight-line direction D. Each of the optical fibers 130B is disposed in a corresponding strip groove 112B. Moreover, each of the light-emitting elements 120B is used for providing a light signal, and in FIG. 3, a referential number 122B is used to represent an optical axis of the light signal. The light signal enters the optical fiber 130B through a light-incident surface 132B of the optical fiber 130B, and the optical axis 122B of the light signal transmitted to the light-incident surface 132B is parallel to the strip grooves 112B and the straight-line direction D.
When the light signal is transmitted to the light-incident surface 132B of the optical fiber 130B, a part of the light signal is reflected by the light-incident surface 132B. In order to avoid a situation that the light signal is reflected back to the light-emitting element 120B to cause damage, in the conventional technique, the light-incident surface 132B of the optical fiber 130B is processed into a slope, and a normal vector N1 of the light-incident surface 132B is not parallel to the optical axis 122B. However, it is time-consuming to process the light-incident surface 132B of the optical fiber 130B into the slope, which leads to a poor production efficiency of the conventional optical electrical module 100B.